box vs window box

box and window box both are nouns.

Word	Noun	Adjective	Verb	Adverb
box	Yes	No	Yes	No
window box	Yes	No	No	No

As nouns, window box is a hyponym of box; that is, window box is a word with a more specific, narrower meaning than box:

box (noun)	window box (noun)
a blow with the hand (usually on the ear)	a long narrow box for growing plants on a windowsill
a (usually rectangular) container; may have a lid
separate partitioned area in a public place for a few people
private area in a theater or grandstand where a small group can watch the performance
the driver's seat on a coach
any one of several designated areas on a ball field where the batter or catcher or coaches are positioned
evergreen shrubs or small trees
the quantity contained in a box
a rectangular drawing
a predicament from which a skillful or graceful escape is impossible